eLua reference manual - SPI module
Overview
This module contains functions for accessing the SPI interfaces of the eLua CPU.
IMPORTANT: right now, only master SPI mode is implemented in eLua.
Functions
clock = spi.setup( id, type, clock, cpol, cpha, databits )
Setup the SPI interface
Arguments:
- id - the ID of the SPI interface.
- type - SPI interface type, can be either spi.MASTER or spi.SLAVE. NOTE: currently, only master SPI mode is supported.
- clock - the clock of the SPI interface.
- cpol - the clock polarity (0 or 1).
- cpha - the clock phase (0 or 1).
- databits - the length of the SPI data word.
Returns: The actual clock set on the SPI interface. Depending on the hardware, this might have a different value than the clock parameter.
spi.sson( id )
Select the SS line (Slave Select) of the SPI interface. This is only applicable for SPI interfaces with a dedicated SS pin.
Arguments: id - the ID of the SPI interface.
Returns: nothing.
spi.ssoff( id )
Deselect the SS line (Slave Select) of the SPI interface. This is only applicable for SPI interfaces with a dedicated SS pin.
Arguments: id - the ID of the SPI interface.
Returns: nothing.
spi.write( id, data1, [data2], ..., [datan] )
Write one or more strings/numbers to the SPI interface.
Arguments:
- id - the ID of the SPI interface.
- data1 - the first string/number to send.
- data2 (optional) - the second string/number to send.
- datan (optional) - the n-th string/number to send.
Returns: nothing.
spi.readwrite( id, data1, [data2], ..., [datan] )
Write one or more strings/numbers to the SPI interface and return the data read from the same interface.
Arguments:
- id - the ID of the SPI interface.
- data1 - the first string/number to send.
- data2 (optional) - the second string/number to send.
- datan (optional) - the n-th string/number to send.
Returns: An array with all the data read from the SPI interface.